In my 05 rubicon with 4.0, I have been running havoline 10w30 regular oil. I actually only have like 28,000 miles on the jeep (don't run it here in the PA winters). Anyways, when I switched to this oil, it seemed like a popular one at the time. Now, I recently purchased a 99GC with 4.0 as well with 117,000 miles. From what i read on the GC forum, I am thinking of running rotella 10w30 oil non-synthetic. I would like to run the same oil in both jeeps so I was thinking of switching the ruby over to 10w30. Any thoughts?
I also have a sludge problem in my GC which I am going to try to address with marvel mistry oil.
The issue with high ZDDP packages is that it not only impacts catalytic converter but DPF's as well (soot/ash formation) so the diesel oils have seen reduced packages much in the same way regular oils have. I used to run T5 when I first built my motor and switched over to Z-rod since it is specifically designed to deal with flat tappet cams. A couple of VOA's for comparison. T5 is OK and probably plenty fine for a stock 4.0.
Originally Posted by samgm2
And yes, I am an exceptional scientist and engineer.
Awesome! Thanks for the VOA's! Amsoil sure does have more than Rotella. I know ZDDP does affect catalytic converters. I view it as a cheaper expense compared to new lifters/camshaft though.
I switched to T5 after having a lifter failure around 87k that cost me a weekend of work and about $700. I had records showing that the PO had regular oil changes done by the dealer. Ironically, I later found out the dealer changed a lifter (not plural) for the PO at 66k (and a 242 at 80k??). Most likely, they didn't pull the camshaft and inspect the lobes. My 87k failure was probably due to Jeep's cheap fix (thanks, Jeep ).
That being said, why the failure at 66k? I have heard a time or two about these 4.0s eating lifters but it makes you wonder if these failures are due to inadequate amounts of ZDDP in oil.
Here are a couple pictures of the carnage. The camera wasn't being kind that day but you get the point.
I tried all sorts of additives to help my lifter tick. None (including MMO) worked. I used M1 5-40 for 6k miles, then found Rotella T6 on Amazon cheaper so I'm using that now. The tick is better, but not gone.
I run Valvoline VR-1 10W-30 non-synthetic. Engine is the quietest it's ever been when using this oil. ZDDP only really impacts the catalytic converter if you are burning oil - remember that catalytic converters have been around since 1975 and ZDDP in oil wasn't really reduced until the late 1990's/early 2000's. I know plenty of people that had 90's cars with 200K+ mile on them on the original converter.
'06 Rubicon Unlimited Sienna Jeep Club: Member #15